Cognitive Neuroscience Ch 5

Sensation

when sensory receptors in the nervous system detect sensory stimuli

Transduction

when sensory inputs are converted into patterns of neural activity

Perception

when sensory information is organized and interpreted resulting in the conscious experience of sensations

Percept

The mental representation of the original stimulus

direction of flow

Stimulation-Transduction-sensation-perception

Sensory receptor

the smallest specialized anatomical structure that collect, filter, and amplify information from the environment

Pattern of sensory system

Thalamus-primary sensory cortex-secondary sensory cortex

Olfactory

which system bypasses the thalamus initially

Thalamus

acts as a gate filtering which information is related to the cerebral cortex for further processing

Thalamus

provides an opportunity for multi sensory integration

thalamus

receives feedback from the cerebral cortex related to attention, perception, and cognitive processes

bidirectional communication

allows for the dynamic modulation of sensory processing based on the current state of the brain and the individuals attentional state

Receptor cells

limited in range of stimuli to which these cells respond

Adaption

the adjustment of the sensory systems sensitivity to the environment (example a reduction of firing rate when a stimulus is continuously present)

Amount of olfactory receptor types

400-450

ipsilateral olfactory cortex

where most olfactory neurons project to

Piriform cortex

located at the ventral junction of the frontal and temporal lobes and where olfactory information targets

Anosmia

a condition where a person loses their sense of smell

Piriform cortex

important for detecting changes in the external odor environment

Piriform cortex

primary olfactory cortex

Orbitofrontal cortex

the secondary olfactory cortex

Orbitiofrontal cortex

essential for identifying and evaluating odors

Gustation

taste

Gustation and Olfaction

chemical senses

Papillae

bumps on tongue involved in gustation, sensation, and secretion

how many taste buds are in the tong cheek and oral cavity

hundreds of thousands

how many receptor cells are on taste buds

dozens to hundreds

Name the five basic tastes

salty, sour, bitter, sweet, and umami

primary gustatory cortex

insulation and frontal operculum

Secondary processing area

orbitofrontal cortex which integrates tastes and smells

Somatosensation

touch

Somatosensation

perception of mechanical stimuli that affect the body (pain, pressure, touch, temp, and position)

Nociception

pain

Nociception

detected by thermal mechanical and multimodal receptors

T or F some nociceptors are myelinated

true

Proprioception

enables sensory and motor systems to represent information about the state and position of the muscles and the limbs

sensory homunculus

a somatotopic representation of the body based on the importance of different body parts (located in primary somatosensory cortex S1)

second somatosensory cortex

displays complex representations about touch like size and texture; information crosses the Corus callousm

Cochlea

where receptors are located in audition

How are sound energy converted to neural signals?

tiny hair cells convert sound energy to neural signals which are then transmitted to the primary auditory cortex

Frequency tuning

determined by location of hair cells along the basilar membrane which varies in width and stiffness

Tonotopic map

formed by cochlear hair cells (20-20,000 Hz)

Mechanoreceptors

mechanical stimulation opens mechanically gated ion channels converting mechanical energy into an electrical signal

True or false hair cells are mechanoreceptors

true

Goals of audition

What and where is the sound

Retina

where the image is inverted and focused in the eye as light passes through

number of photoreceptors

260 million

Rods

contain the photopigment RHODOPSIN and are highly sensitive to low levels of light (photoreceptor)

Cone

contain PHOTOPSIN and require more intense light they recover more rapidly than rods and are more active during the day (photoreceptor)

Bipolar cells

connected by rods and cones, which synapse with ganglion cells, the output layer of the retina

Fovea

the central region of the retina that provides high acuity detailed vision; it is free of overlying ganglion cell axons and blood vessels

How much of our vision is what we see in the fovea

70 percent

What are the connections between cones and neurons like in the central fovea?

They have one to one connections supporting high spatial resolution (within 1-2 degrees of visual angle)